$result = $this->drupalGet($url, $options);
$this->assertSession()->statusCodeEquals(200);
$this->assertEquals('application/json', $this->getSession()->getResponseHeader('Content-Type'));
$result = $this->drupalGet($url, $options);
$this->assertSession()->statusCodeEquals(200);
$this->assertEquals('application/json', $this->getSession()->getResponseHeader('Content-Type'));